Android：使用帶光標的sqlite數據庫崩潰

Question

我是android開發的新手，正在嘗試使用sqlite創建聯系人管理器列表，但是在使用游標訪問我的sqlite數據庫時遇到了麻煩。 我有2個活動，一個活動用於向數據庫添加新聯系人，另一個活動用於為數據庫讀取聯系人。

這是我的主要活動：

package com.example.contactmanager;

import java.util.ArrayList;

public class MainActivity extends ActionBarActivity {

private SQLiteDatabase sdb;
private TestDBOpenHelper tdb;
private ArrayList<String> al_strings;
private ArrayAdapter<String> aa_strings;
private ListView lv;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    tdb = new TestDBOpenHelper(this, "test.db", null, 1);
    sdb = tdb.getReadableDatabase();

    lv = (ListView) findViewById(R.id.lv);
    al_strings = new ArrayList<String>();
    aa_strings = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, al_strings);

    lv.setAdapter(aa_strings);

    String[] columns = { "ID", "NAME", "PHONE_NUMBER", "EMAIL" };
    Cursor c = sdb.rawQuery("test", columns);

    c.moveToFirst();        
    while (c.isAfterLast() == false) {
        al_strings.add(c.getString(c.getColumnIndex("NAME")));
        al_strings.add(c.getString(c.getColumnIndex("PHONE_NUMBER")));
        al_strings.add(c.getString(c.getColumnIndex("EMAIL")));
        c.moveToNext();
    }

    Button button = (Button) findViewById(R.id.button);
    button.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            Intent nextScreen = new Intent(getApplicationContext(),
                    AddContact.class);
            startActivity(nextScreen);
        }
    });
}

public boolean listUpdate(Integer id, String name, String phone, String mail) {

    SQLiteDatabase db = tdb.getWritableDatabase();
    ContentValues cv = new ContentValues();
    cv.put("NAME", name);
    cv.put("PHONE_NUMBER", phone);
    cv.put("EMAIL", mail);
    db.update("test", cv, "id = ? ", new String[] { Integer.toString(id) });
    return true;

}

public Cursor getList() {
    SQLiteDatabase sdb = tdb.getReadableDatabase();

    // the columns that we wish to retrieve from the tables
    String[] columns = { "ID", "NAME", "PHONE_NUMBER", "EMAIL" };

    Cursor c = sdb.rawQuery("test.db", columns);
    return c;
}

// overridden method that will clear out the contents of the database
/*@Override
protected void onDestroy() {
    super.onDestroy();

    // run a query that will delete all the rows in our database
    String table = "test";
    String where = null;
    String where_args[] = null;
    sdb.delete(table, where, where_args);
}*/

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
  }
}

TestDBOpenHelper是我的用於初始化數據庫的類：

public class TestDBOpenHelper extends SQLiteOpenHelper {
// constructor for the class here we just map onto the constructor of the
// super class

public TestDBOpenHelper(Context context, String name,
        CursorFactory factory, int version) {
    super(context, name, factory, version);
}

// overridden method that is called when the database is to be created

public void onCreate(SQLiteDatabase db) {
    // create the database
    db.execSQL(create_table);
}

// overridden method that is called when the database is to be upgraded
// note in this example we simply reconstruct the database not caring for
// data loss
// ideally you should have a method for storing the data while
// you are reconstructing the database

public void onUpgrade(SQLiteDatabase db, int version_old, int version_new) {
    // drop the tables and recreate them
    db.execSQL(drop_table);
    db.execSQL(create_table);
}

// a bunch of constant strings that will be needed to create and drop
// databases

private static final String create_table = "create table test ("
        + "ID integer primary key autoincrement, " + "NAME string,"
        + "PHONE_NUMBER string, " + "EMAIL string" + ");";

private static final String drop_table = "drop table test";
}    

這是我的第二項活動，用於添加聯系人：

public class AddContact extends Activity {

EditText inputName;
EditText inputPhone;
EditText inputMail;
private TestDBOpenHelper tdb;
private MainActivity ma;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.second_activity);

    tdb = new TestDBOpenHelper(this, "test.db", null, 1);

    inputName = (EditText) findViewById(R.id.name);
    inputPhone = (EditText) findViewById(R.id.ed_pho);
    inputMail = (EditText) findViewById(R.id.ed_ema);

    Button btnPrevScreen = (Button) findViewById(R.id.btn_add);

    btnPrevScreen.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

            Bundle extras = getIntent().getExtras();
            if(extras != null) {
                int Value = extras.getInt("ID");
                if(Value>0) {
                    if(ma.listUpdate(0, inputName.getText().toString(), 
                            inputPhone.getText().toString(),
                            inputMail.getText().toString())) {
                        Toast.makeText(getApplicationContext(), "Updated",
                                Toast.LENGTH_SHORT).show();
                    }
                    else
                        Toast.makeText(getApplicationContext(), "Not updated",
                                Toast.LENGTH_SHORT).show();
                }
                else {
                    if(addContact(inputName.getText().toString(), 
                            inputPhone.getText().toString(),
                            inputMail.getText().toString())) {
                        Toast.makeText(getApplicationContext(), "Contact Added",
                                Toast.LENGTH_SHORT).show();
                    }
                    else
                        Toast.makeText(getApplicationContext(), "Error",
                                Toast.LENGTH_SHORT).show();
                }
                Intent prevScreen = new Intent(getApplicationContext(), MainActivity.class);
                startActivity(prevScreen);
            }
        }
    });
}

public boolean addContact(String name, String phone, String mail) {

    SQLiteDatabase sdb = tdb.getWritableDatabase();
    ContentValues cv = new ContentValues();

    cv.put("NAME", name);
    cv.put("PHONE_NUMBER", phone);
    cv.put("EMAIL", mail);

    sdb.insert("test", null, cv);

    return true;
  }
}

問題在這里，在我的MainActivity上：

Cursor c = sdb.rawQuery("test", columns);

當我對此發表評論時，我的應用程序“運行”（可以從nexus 5啟動它），我通過調試模式發現，正是這條線使其崩潰（我認為）。

這是LogCat：

 02-27 17:59:04.408: E/SQLiteLog(28845): (1) near "test": syntax error 02-27 17:59:04.414: D/AndroidRuntime(28845): Shutting down VM 02-27 17:59:04.418: E/AndroidRuntime(28845): FATAL EXCEPTION: main 02-27 17:59:04.418: E/AndroidRuntime(28845): Process: com.example.contactmanager, PID: 28845 02-27 17:59:04.418: E/AndroidRuntime(28845): java.lang.RuntimeException: Unable to start activity 

ComponentInfo {com.example.contactmanager / com.example.contactmanager.MainActivity}：android.database.sqlite.SQLiteException：在“ test”附近：語法錯誤（代碼1）：，而在編譯時：test 02-27 17：59：04.418 ：E / AndroidRuntime（28845）：位於android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2298）02-27 17：59：04.418：E / AndroidRuntime（28845）：位於android.app.ActivityThread.handleLaunchActivity（ActivityThread。 java：2360）02-27 17：59：04.418：E / AndroidRuntime（28845）：at android.app.ActivityThread.access $ 800（ActivityThread.java:144）02-27 17：59：04.418：E / AndroidRuntime（28845） ）：在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1278）02-27 17：59：04.418：E / AndroidRuntime（28845）：在android.os.Handler.dispatchMessage（Handler.java:102） 02-27 17：59：04.418：E / AndroidRuntime（28845）：在android.os.Looper.loop（Looper.java:135）02-27 17：59：04.418：E / AndroidRuntime（28845）：在Android。 app.ActivityThread.main（ActivityThread.java:5221）02-27 17：59：04.418：E / AndroidRuntime（28845）：at java.lang.reflect.Method.invoke（本機方法）02-27 17：59：04.418：E / AndroidRuntime（28845）：at java.lang.reflect.Method.invoke（Method.java:372）02-27 17 ：59：04.418：E / AndroidRuntime（28845）：at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:899）02-27 17：59：04.418：E / AndroidRuntime（28845）：at com.android.internal.os.ZygoteInit.main（ZygoteInit.java:694）02-27 17：59：04.418：E / AndroidRuntime（28845）：原因：android.database.sqlite.SQLiteException：在“測試”附近：語法錯誤（代碼1）：，編譯時：測試02-27 17：59：04.418：E / AndroidRuntime（28845）：位於android.database.sqlite.SQLiteConnection.nativePrepareStatement（本地方法）02-27 17：59：04.418 ：E / AndroidRuntime（28845）：位於android.database.sqlite.SQLiteConnection.acquirePreparedStatement（SQLiteConnection.java:889）02-27 17：59：04.418：E / AndroidRuntime（28845）：位於android.database.sqlite.SQLiteConnection。 prepare（SQLiteConnection.java:500）02-27 17：59：04.418：E / AndroidRuntime（28845）：位於android.database.sqlit e.SQLiteSession.prepare（SQLiteSession.java:588）02-27 17：59：04.418：E / AndroidRuntime（28845）：位於android.database.sqlite.SQLiteProgram。（SQLiteProgram.java:58）02-27 17:59 ：04.418：E / AndroidRuntime（28845）：在android.database.sqlite.SQLiteQuery。（SQLiteQuery.java:37）02-27 17：59：04.418：E / AndroidRuntime（28845）：在android.database.sqlite.SQLiteDirectCursorDriver .query（SQLiteDirectCursorDriver.java:44）02-27 17：59：04.418：E / AndroidRuntime（28845）：at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory（SQLiteDatabase.java:1316）02-27 17：59：04.418 ：E / AndroidRuntime（28845）：位於android.database.sqlite.SQLiteDatabase.rawQuery（SQLiteDatabase.java:1255）02-27 17：59：04.418：E / AndroidRuntime（28845）：位於com.example.contactmanager.MainActivity。 onCreate（MainActivity.java:44）02-27 17：59：04.418：E / AndroidRuntime（28845）：at android.app.Activity.performCreate（Activity.java:5933）02-27 17：59：04.418：E / AndroidRuntime（28845）：位於android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1105 ）02-27 17：59：04.418：E / AndroidRuntime（28845）：位於android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2251）02-27 17：59：04.418：E / AndroidRuntime（28845）：..還有10個

我試圖解決這個問題已經好幾個小時了，但是我找不到辦法，任何幫助都是有福的。 這可能是我的一個愚蠢錯誤，請原諒我。

Answer 1

您需要編寫完整的SQL命令。 Cursor cursor = database.rawQuery("select * from exectable", null);